Digital cameras typically capture images electronically and ultimately store the images as bits (ones and zeros) on a solid-state memory. Flash memory is the most common storage for digital cameras. Flash memory contains one or more electrically-erasable read-only-memory (EEPROM) integrated circuit chips that allow reading, writing, and block erasing.
Early digital cameras required the user to download or transfer the images from the flash memory within the digital camera to a personal computer (PC). A standard serial cable was most widely used. However, the limited transfer rate of the serial cable and the large size of the digital images made such serial downloads a patience-building experience. Serial downloads could easily take half an hour for only a few dozen images.
Digital camera manufacturers solved this problem by placing the flash memory chips on a small removable card. The flash-memory card could then be removed from the digital camera, much as film is removed from a standard camera. The flash-memory card could then be inserted into an appropriate slot in a PC, and the image files directly copied to the PC.
FIG. 1A shows a conventional scheme in which a flash memory card and adapter are employed for transferring images from a digital camera to a PC. Generally, digital camera 14 will employ a flash memory card containing one or more flash memory chips that are used to store data pertaining to images taken by users of the camera. In the illustrated example, the flash memory chip(s) are contained in a CompactFlash™ card 16 (CompactFlash is a trademark of SanDisk Corp. of Sunnyvale, Calif.), which can be removed from digital camera 14 by pressing a card-eject button.
Typically, laptop and notebook computers have one or more PC-card (earlier known as PCMCIA, Personal Computer Memory Card International Association) slots that can receive PCMCIA cards. In this conventional scheme, a CF-to-PCMCIA adapter 10 is employed to enable a PC or laptop computer to read data stored on CompactFlash card 16 as if it were stored on a PCMCIA card. As shown in FIG. 1A, CF-to-PCMCIA adapter 10 contains a connector interface disposed in an opening that receives CompactFlash card 16. FIG. 1B shows CF-to-PCMCIA adapter 10 with CompactFlash card 16 inserted.
As shown in FIG. 1C, a computer such as notebook PC 20 can read data stored on a PCMCIA card via either a PCMCIA reader 12 connected to the PC via a parallel or USB cable, or directly via a built-in PCMCIA slot 22. Once the PCMCIA is inserted into the reader or the PCMCIA slot, the user merely has to copy the image files from CompactFlash card 16 to the hard disk of PC 20. Since high-speed parallel buses are used, transfer is rapid, about the same speed as accessing the hard disk. This greatly enhances the transfer speed when compared with the serial cable link discussed above.
Although the CompactFlash card format is relatively small, being not much more than an inch square, other smaller cards have recently emerged. For example, several of such smaller flash media cards are shown in FIG. 2A, including a SmartMedia™ (SmartMedia is a trademark of the SSFDC Forum of Tokyo, Japan).card 24, which is less than half an inch long, yet has enough flash memory capacity for dozens of images. The SmartMedia card may be read in a manner similar to that discussed above with a SmartMedia-to-PCMCIA adapter 10′. Depending on the manufacturer and card capacity, different adapters 10′ may be required for different memory capacities of SmartMedia card 24.
Other kinds of flash-memory cards that are being championed by different manufacturers include MultiMediaCard™ (MMC) 28 and the related Secure Digital Card (SD) 26. MMC is a trademark of SanDisk Corp. of Sunnyvale, Calif. while SD is controlled by the SD Group that includes Matsushita Electric Industrial Co., SanDisk Corporation, Toshiba Corp. Another emerging form factor from Sony is Memory Stick 18. Typically, memory stick devices may be read using a PCMCIA/Floppy adapter while MMC may be read with a floppy adapter.
The different physical shapes and pin arrangements of cards 24, 26, 28 and Memory Stick 18 prevent their use in CF-to-PCMCIA adapter 10. Indeed, most of these cards 24, 26, 28 have less than a dozen pins, while CompactFlash card 16 has a larger 50-pin interface. Furthermore, serial data interfaces are used in the smaller cards 24, 26, 28, while a parallel data bus is used with CompactFlash card 16.
FIG. 2B shows a Memory Stick-to-PCMCIA adapter that includes an active converter chip 11. Memory Stick 18 fits into an opening in Memory Stick-to-PCMCIA adapter 15, allowing adapter 15 and the Memory Stick to be plugged into a standard PCMCIA slot on a PC in a manner similar to CF-to-PCMCIA adapter 10. However, rather than providing a passive adaptor function, adapter 15 employs active converter chip 11 to convert the serial data format of Memory Stick 18 to the parallel data format of a 68-pin PCMCIA slot. Inclusion of converter chip 11 in adapter 15 significantly increases the cost and complexity of adapter 15 compared to CF-to-PCMCIA adapter 10.
While the advances in flash-memory card technology are useful, the many different card formats present a confusing array of interface requirements to a PC. Different adapters are needed for each of the card formats. PCMCIA card reader 12 can be replaced with other format readers, such as a SmartMedia Card reader, and even some multi-standard readers are available, such as a universal reader from Lexar Media that reads CompactFlash or SmartMedia in addition to PCMCIA.
Occasionally, a user may remove a flash media from a host device, such as a digital camera, PDA (Personal Digital Assistant), MP3 player, etc., while the host device is reading to or writing from the card. Media card removal, particularly during the writing, but also sometimes during the reading, may destroy the card formatting, resulting, in most cases, in making the data unreadable by the host and possibly other interfacing devices. In addition, flash media card formatting and file information may become corrupted or lost due to other causes, such as power failure during read or write operations, faulty programs, faulty host device or reader, high level “erasing” of files by a user, who later wants to recover such files, or other causes. As a result, the content on the card cannot be read and/or accessed.
Currently, there exists techniques for recovering data from such media through use of a computer and (generally) some time of flash media “reader” or other type of flash media interface device. However, when someone is using a device that stores data on flash media in the field, such as a tourist using a digital camera on an overseas trip, the user may not have access to a computer and/or reader. What is clearly needed is a field-operable, stand-alone apparatus that allows the regeneration and recovery of corrupted media of all types, without having to rely on the availability of a computer or reader. Furthermore, it would be advantageous if such a apparatus could read a variety of different card formats.